Production of capsules and particles for improvement of food products

ABSTRACT

The present invention is related to the production of capsules or particles of micro and nanometric size, for introduction into food, using stable electrified coaxial jets of two immiscible liquids with diameters in the micro and nanometric range. An aerosol of charged structured droplets forms when the jets dissociate by capillary instabilities. The structured droplets, which are mano-dispersed in size, contain a first liquid (generally the material desired to be added) that is surrounded by a second liquid. Generally the second liquid provides a barrier or protective coating which allows the addition of the first liquid to a food product without adversely affecting the organoleptic or other properties of the food product.

This application is a reissue application of U.S. Pat. No. 6,989,169,filed as application Ser. No. 10/627,387 on Jul. 25, 2003, which is acontinuation of application No. PCT/US02/02787, filed Jan. 30, 2002,which claimed the benefit of ES 200100231, filed Jan. 31, 2001.

This application is a continuation of PCT Application No. US 02/02787,filed on Jan. 30, 2002, entitled “Production of Capsules and Particlesfor Improvement of Food Products,” which claims priority from SpanishPatent No. 200100231, filed on Jan. 31, 2001.

FIELD OF INVENTION

The invention relates generally to the field of production of smallparticle and/or capsules with extremely small and uniform sizes usingelectro hydrodynamic (EHD) techniques. The particles and/or capsules asprepared by this invention are especially adapted for use in foodproducts and allow, for example, the addition of enhancing or functionalfood additives without adversely effecting the organoleptic or otherproperties of the food products.

BACKGROUND OF THE INVENTION

The present invention uses electro hydrodynamic (EHD) forces to generatecoaxial jets and to stretch them out to the desired sizes. Forappropriate operating conditions, a liquid flow rate, in the form of amicro/nanometric-sized jet, is issued from the vertex of a Taylor cone(i.e., a liquid meniscus which adopts a conical shape due to the balancebetween the electric stresses and the interfacial tension). Forappropriate operating conditions, a liquid flow rate, in the form of amicro/nanometric jet, is issued from the vertex of such a Taylor cone.The break up of this jet gives rise to an aerosol of charged droplets,which is called electrospray. This configuration is widely known aselectrospray in the cone-jet mode (Cloupeau et al., J. Electrostatics,22, 135-159, 1992). The scaling laws for the emitted current and thedroplet size of the electrospray are given in the literature (see, e.g.,Fernández de la Mora et al., J. Fluid Mech., 260, 155-184, 1994;Gañán-Calvo et al., J. Aerosol Sci., 28, 249-275, 1997; Gañán-Calvo,Phys. Rev. Lett., 79, 217-220, 1997; Hartman et al., J. Aerosol Sci.,30, 823-849, 1999). Electrospray is a technique which has satisfactoryproved its ability to generate steady liquid jets and monodisperseaerosols with sizes ranging from a few of nanometers to hundred ofmicrons (Loscertales et al., J. Chem. Phys., 103, 5041-5060,1995).Generally, in most electrospray experiments, a unique liquid (orsolution) forms the Taylor cone. However, the procedure described in theU.S. Pat. No. 5,122,670 (Jun. 16, 1992) and U.S. Pat. No. 5,517,260(Oct. 20, 1992), entitled “Multilayer Flow Electrospray Ion Source UsingImproved Sheath Liquid” and “Method and Apparatus for Focusing Ions inViscous Flow Jet Expansion Region of an Electrospray Apparatus,”respectively, involve two or more miscible liquids which were properlyinjected to be mixed in the Taylor cone to improve the transmission ofions, and the stability and sensitivity of a mass spectrometer. Otherpatents of interest to the present invention relating to electrospraytechnology include, for example, U.S. Pat. No. 4,885,076 (Dec. 5, 1989),U.S. Pat. No. 4,977,785 (Dec. 18, 1990), U.S. Pat. No. 5,170,053 (Dec.8, 1992), U.S. Pat. No. 5,171,990 (Dec. 15, 1992), U.S. Pat. No.5,393,975 (Feb. 28, 1995), and Re. 35,413 (Dec. 31, 1996).

Recently there has been significant interest in providing food productshaving increased health and/or nutritional benefits. Such improved foodproducts and/or such functional foods generally have one or more addedingredients which are included to provide a specific health and/ornutritional benefit. Thus, food such as breads with added carbohydrates,cereals with added vitamins and/or minerals, foods in which undesirablecomponents are reduced by the addition of other more desirablecomponents (e.g., replacement of fat with a fat substitute), soyprotein-containing foods, fiber-containing foods, protein-enrichedfoods, omega fatty acid-containing foods, calcium or other mineral orvitamin enriched foods, dietary supplement-containing foods, and thelike are becoming increasing popular with a health conscious public.Such improved or functional foods may contribute to overall well beingand/or reduce the risk of certain diseases or conditions.

Unfortunately, it is often difficult to incorporate such ingredients infood products without adversely affecting the organoleptic and/or otherproperties of the food product. Ideally, it desired to provide such animproved or functional food product which has taste, texture, and otherorganoleptic properties as close to, and perhaps even superior to, theconventional food product without the added ingredients. In many cases,however, such additives provide undesirable flavor, aroma, textural, orsimilar properties to the foods to which they are added. In some cases,the enhancing additives may even react or complex with other componentsof the food product (including, for example, other desired enhancingadditives) thereby adversely affecting the food product in some manneror making the additives less readily available for absorption and use inthe body upon consumption.

Thus, it would be desirable to provide improved and/or functional foodswherein such enhancing additives are contained in a form which preventsor significantly reduces impairment of the organoleptic or otherproperties of the foods to which they are added. The present inventionprovides such improved and/or functional foods. For example, the presentinvention allows for the incorporation of enhancing additives whichwould, except for the use of the present invention, normally result intaste, aroma, textural, or other organoleptic defects when added to foodproducts. Thus, the present invention allows for the product of improvedand/or functional foods without, or with significantly reduced,organoleptic defects normally associated with such enhancing additives;indeed, the improved and/or functional foods of this invention closelymimic the corresponding conventional food without such enhancingadditives.

SUMMARY OF THE INVENTION

The present invention is related to the production of capsules orparticles of micro and nanometric size, for introduction into food,using stable electrified coaxial jets of two immiscible liquids withdiameters in the micro and nanometric range. An aerosol of chargedstructured droplets forms when the jets dissociate by capillaryinstabilities. The structured droplets, which are mono-dispersed insize, contain a first liquid (generally the material desired to beadded) that is surrounded by a second liquid. Generally the secondliquid provides a barrier or protective coating which allows theaddition of the first liquid to a food product without adverselyaffecting the organoleptic or other properties of the food product.

A variety of devices and methods are disclosed which allow for theformation of the stable electrified coaxial micro-jets. In preferredembodiments, the inner fluid is a liquid which forms a food or foodadditive, which would be desirable to have in, but which cannot be addedto food for some reason (e.g., taste defects or reaction with othercomponents in the food product). A non-toxic outer liquid surrounds theinner one. Coaxial jets break up into structured droplets where theinner fluid (liquid food) is coated with the outer one (liquid carriercoating). The coating provided by the outer liquid prevents either thetaste defects or reactive effects of the liquid food from having itsundesirable consequences. These embodiments provide spherical particlesof liquid food coated with a layer of another non-toxic material (e.g.,a polymer that is degraded in the gastrointestinal tract) and may or maynot be a food product.

The outer diameter of the coaxial jets can have a diameter in the rangeof from about 80 nanometers to about 100 microns. The stable jet ismaintained by the action of electrical stresses when both liquids arefed at appropriate flow rates. Mono-dispersed aerosols from theinvention are characterized by having a high degree of uniformity inparticle size. Particles have the same diameter with a deviation indiameter from one particle to another in a range of about ±2 (or less)to about ±10 percent.

This invention provides a method to form stable coaxial electrified jetsof two non-miscible liquids via EHD. This invention also provides amono-disperse aerosol of structured particles or capsules as a result ofthe break up of the coaxial jets. Capsules are characterized by havingthe same diameter with a deviation in diameter from one particle toanother in a range of from about ±2 (or less) to about ±10 percent.These capsules may be desiccated following dispersion and then added tofood.

One advantage of the present invention is that the resulting dropletshave an uniform size, and that, depending of the properties of theliquids and the injected flow rates, such a size can be easily variedfrom tens of microns to a few nanometers. Another advantage of theinvention is that capsules are created with a relatively small amount ofenergy. Another feature of the invention is that the surface area of agiven substance can be maintained while decreasing the overall amount ofthe substance (e.g., a fiber particle coated with oil). This can allowintroduction of components that are generally incompatible with a food(e.g., introduction of lactase in milk) by coating the component. Yetanother feature of the invention is the use production of time-releasecomponents to control delivery of the contents of the capsule (e.g.,carbohydrates coated to allow a systematic delivery over, for example, aone to twelve-hour period).

Another advantage of this invention results from the fact that breakingup of the jet gives rise to structured micro/nanometric droplets. Insome particular applications, the outer liquid is a solution containingmonomers, which under appropriate excitation polymerize to producemicro/nanometric capsules. When uncharged droplets are required, theaerosol can be easily neutralized by corona discharge.

These and other aspects, advantages, and features will become apparentto those skilled in the art upon reading this disclosure in combinationwith the figure provided.

BRIEF DESCRIPTION OF THE DRAWING

The FIGURE provides a schematic representation of an apparatus 100suitable for the formation of capsules and particles for incorporationinto food products by generation of compound jets via EHD. A structuredTaylor cone 20 forms at the ends 18 the electrified needles 14 and 16when inner liquid 10 and outer liquid 12, respectively, are injected atappropriate flow rates through their respective needle tips 18. At leastone needle (in this case needle 16) is connected at a potentialdifference 28 with respect to a reference electrode 24 which has a hole26 there through. In one preferred embodiment, the potential difference28 between the needles 14 and 16 and the reference electrode 24 is a fewkV. Two concentric jets 21, one of them surrounding the other, issuefrom the tip (i.e., cone vertex) of Taylor cone 20. The concentric jets21 break up eventually by varicose instabilities giving rise to anaerosol of compound drops 22 with the inner liquid 10 (dark grey)surrounded by the outer one 12 (lighter gray). Chamber 30 contains adielectric atmosphere (i.e., gas, liquid, or vacuum) in which thecompound drops 22 are formed. Compound drops 22 can be removed fromchamber 30 via hole 26.

DETAILED DESCRIPTION

The present invention is related to the production of capsules orparticles of micro and nanometric size, for introduction into food,using stable electrified coaxial jets of two immiscible liquids withdiameters in the micro and nanometric range. An aerosol of chargedstructured droplets forms when the jets dissociate by capillaryinstabilities. The structured droplets, which are mono-dispersed insize, contain a first liquid (generally the material desired to beadded) that is surrounded by a second liquid. Generally the secondliquid provides a barrier or protective coating which allows theaddition of the first liquid to a food product without adverselyaffecting the organoleptic or other properties of the food product.

In the present invention, liquids are injected at appropriate flow ratesthroughout metallic needles connected to a high voltage supply. Theneedles can be arranged either concentrically or one of them surroundingthe others. Moreover, if the electrical conductivity of one or moreliquid is sufficiently high, then the liquid can be charged through itsbulk. In that case a non-metallic needle (i.e., silica tube) can be usedto inject the liquid.

The present invention uses two or more immiscible liquids (or poorlymiscible) to form, by means of EHD forces, a structured Taylor conesurrounded/immersed by a dielectric atmosphere (gas, liquid, or vacuum).Preferably the dielectric atmosphere is an inert gas (i.e., non-reactivewith at least the outermost liquid) or a vacuum. An outer meniscussurrounding the inner ones forms the structure of the cone. A liquidthread is issued from the vertex of each one of the menisci in such away that a compound jet of co-flowing liquids is formed. The structured,highly charged micro/nanometric jet issues from the vertex of the Taylorcone, and eventually breaks up to form a spray of structured, highlycharged, monodisperse micro/nanometric droplets. The term structured jetas used herein refers to either quasi-cylindrical coaxial jets or a jetsurrounding the others. The outer diameter of the jet generally rangesfrom about 50 microns to a few nanometers. The term spray of structured,highly charged, monodisperse, micro/nanometric droplets as used hereinrefers to charged droplets formed by concentric layers of differentliquids or by an outer droplet of liquid surrounding smaller droplets ofimmiscible liquids (or emulsions)/a liquid engulfing smaller droplets ofimmiscible liquids. The outer diameter of the droplets ranges from 100microns to a few of nanometers.

A variety of devices and methods are disclosed which allow for theformation of the stable electrified coaxial micro-jets. In preferredembodiments, the inner fluid is a liquid which forms a food or foodadditive, which would be desirable to have in, but which cannot be addedto food for some reason (e.g., taste defects or reaction with othercomponents in the food product). A non-toxic outer liquid surrounds theinner one. Coaxial jets break up into structured droplets where theinner fluid (liquid food) is coated with the outer one (liquid carriercoating). The coating provided by the outer liquid prevents either thebad taste or reactive effects of the liquid food from having itsundesirable consequences. These embodiments provide spherical particlesof liquid food coated with a layer of another non-toxic material (e.g.,a polymer that is degraded in the gastrointestinal tract) and may or maynot be a food product.

In general, the present invention uses a device having a number N offeeding tips of N liquids, such that a flow rate Qi of the i-th liquidflows through the i-th feeding tip, where i is a value between 2 and N.The feeding tips are arranged concentrically and each feeding tip isconnected to an electric potential V₁ with respect to a referenceelectrode. The i-th liquid that flows through the i-th feeding tip isimmiscible or poorly miscible with liquids (i+1)-th and (i−1)-th. Anelectrified capillary structured meniscus with noticeable conical shapeforms at the exit of the feeding tips. A steady capillary coaxial jet,formed by the N liquids, such that the i-th liquid surrounds the(i+1)-th liquid, issues from the cone apex. Generally, such capillaryjet has a diameter ranging typically from 100 microns and 15 nanometers.This diameter is much smaller than the diameters of the feeding tips ofthe N liquids.

The feeding tips may also be arranged such that the outer liquidsurrounds the rest of the feeding tips. In this case, at the exit of thefeeding tips, an electrified capillary meniscus is formed withnoticeable conical shape, whose apex issues an steady capillary compoundjet formed by the N co-flowing liquids, in such a way that, for example,liquid 1 surrounds the rest of the liquids. The N feeding tips of thedevice have diameters that may vary between 0.01 mm and 5 mm. The flowrates of the liquids flowing through the feeding tips may vary betweenabout 10⁻¹⁷ m³/s and about 10⁻⁷ m³/s. When the distance between thefeeding tip and the reference electrode is between about 0.01 mm andabout 5 cm, the applied electric potential generally is in the range ofabout 10 V to about 30 KV.

In the particular case having only two feed tips (i.e., N=2; see theFIGURE), the present invention provides an apparatus comprising:

a) a feeding tip 1 through which liquid 1 flows at a flow rate Q₁ to aexit 1 and it is connected to an electric potential V₁; and

b) a feeding tip 2 through which liquid 2 flows at a flow rate Q₂ to anexit 2 and it is connected to an electric potential V₂,

wherein the feeding tip 2 is surrounded by liquid 1 and such that V₁ andV₂ are differential values with respect to an electrode connected to areference potential, whereby an electrified capillary meniscus withnoticeable conical shape is formed at the exit of the feeding tips 1 and2, whereby a steady capillary jet is formed by liquids 1 and 2, suchthat liquid 1 completely surrounds liquid 2 as they issue from the exits1 and 2, wherein liquids 1 and 2 are immiscible or poorly miscible.Generally such a capillary jet has a diameter of about 100 microns toabout 15 nanometers; this diameter is smaller than the characteristicdiameter of the electrified capillary liquid meniscus from which it isemitted.

Two basic configurations are discussed above that allow setting up aflow of two immiscible liquids that, by the unique action of the electrohydrodynamic (EHD) forces, results in the formation of a steady,structured, micro/nanometric sized capillary jet. This structuredmicro/nanometric sized capillary jet is immersed in a dielectricatmosphere (immiscible with the outermost liquid forming the jet) thatmight be a gas, liquid, or vacuum.

The basic device used in both configurations of the above describedapparatus comprises: (1) a means-to feed a first liquid 1 through ametallic tube T₁, whose inner diameter ranges approximately between 1and 0.4 mm, respectively; (2) a means to feed a second liquid 2,immiscible with liquid 1, through a metallic tube T₂, whose outerdiameter is smaller than the inner diameter of T₁. In this case, T₁ andT₂ are concentric (the end of the tubes does not need to be located atthe same axial position); (3) a reference electrode (e.g., a metallicannulus for instance) placed in front of the needle exits at a distancebetween about 0.01 and about 50 mm; the axis of the hole of the annulusis aligned with the axis of T₁; and (4) a high voltage power supply,with one pole connected to T₁ and the other pole connected to thereference electrode. T₁ and T₂ might not be connected to the sameelectric potential. All the elements are immersed in a dielectricatmosphere that might be a gas, a liquid immiscible with liquid 1, orvacuum. Generally the dielectric atmosphere will be contained within achamber as shown in the FIGURE. Of course, if the dielectric atmosphereis air, the chamber is simply the air surround the Taylor cone andconcentric jets. A part of the generated aerosol, or even the structuredjet, may be extracted through the orifice in (3) to characterize it orto process it.

The EHD forces must act, at least, on one of the two liquids, althoughthey may act on both. We term driver liquid the one upon which the EHDforces act to form the Taylor cone. In the first configuration, thedriver liquid flows through the annular space left between T₁ and T₂,whereas in the second configuration the driver liquid flows through T₂,and the second liquid flows through the annular gap between T₁ and T₂.In any case, the electrical conductivity of the driver liquid must havea value sufficiently high to allow the formation of the Taylor cone.

Referring to the first configuration, when liquid 1 (the driver liquid)is injected at an appropriate flow rate Q₁ and an appropriate value ofthe electric potential difference is applied between T₁ and an electrodeand, liquid 1 develops a Taylor cone, whose apex issues a steady chargedmicro/nanometric jet (steady cone-jet mode). The characteristic conicalshape of the liquid meniscus is due to a balance between the surfacetension and the electric forces acting simultaneously and/at themeniscus surface. The liquid motion is caused by the electric tangentialstress acting on the meniscus surface, pulling the liquid towards thetip of the Taylor cone. At some point, the mechanical equilibrium justdescribed fails, so that the meniscus surface changes from conical tocylindrical. The reasons behind the equilibrium failure might be due,depending on the operation regime, to the kinetic energy of the liquidor to the finite value of the liquid electrical conductivity. The liquidthus ejected due to the EHD force, should be continuously made up for anappropriate injection of liquid through T₁ in order to achieve a steadystate. The stability of this precursor state may well be characterizedby monitoring the electric current/transported by the jet and theaerosol collected at the electrode. Depending on the properties ofliquid 1 and on Q₁, the liquid motion inside the Taylor cone may bedominated by viscosity, in which case, the liquid velocity everywhereinside the cone is mainly pointing towards the cone tip. Otherwise, theflow inside the cone may exhibit strong re-circulations, which should beavoided to produce structured micro/nanometric jets. Provided the flowis dominated by viscosity, one may then proceed to form the structuredmicro/nanometric jet. To do that, one continuously supplies liquid 2through T₂. The meniscus of liquid 2, which develops inside the Taylorcone formed by liquid 1, is sucked towards the cone tip by the motion ofliquid 1. Under certain operation conditions, which depend on theproperties of both liquids (and on the liquid-liquid properties), themeniscus of liquid 2 may develop a conical tip from which amicro/nanometric jet is extracted by the motion of liquid 1. In thissituation, there may exist regimes where the jet of liquid 2 flowscoaxially with liquid 1. As before, liquid 2 is continuously supplied toT₂ at a flow rate Q₂ in order to achieve a steady state.

When the device operates in the second configuration, the procedure isanalogous, except that the motion of the driver liquid does not need tobe dominated by viscosity.

Although not wishing to be limited by theory, the present study suggeststhat formation of coaxial liquid jets requires that the values of thesurface tension of the different fluid pairs appearing in the problemsatisfy the inequality S_(ai)−S_(ao)>S_(oi), where S_(ai) is the surfacetension of liquid 2 and the dielectric atmosphere, S_(ao) is the surfacetension of liquid 1 and the dielectric atmosphere, and S_(oi) is theinterfacial tension of liquid 1-liquid 2, respectively.

To give an idea of the typical values of the different parametersappearing in the process, the table below provides experimentalmeasurements of the electric current transported by the jet fordifferent flow rates of the inner liquid keeping fixed the flow rate ofthe outer liquid.

Q₁ = 50 ml/min Q₂ (ml/min.) 0.67 0.83 1.17 1.50 1.84 2.17 I (mAmp.) 1.11.3 1.5 1.7 1.9 2.0Notice that in this example, corresponding to the case where Q₁ is muchlarger than Q₂, the value of the current I follows the well-knownelectrospray law Iμ Q₂ ^(1/2).

To produce nanometric capsules through the procedure of the presentinvention a photopolymer may be used as the external liquid. Indeed, thebreak up of the structured jet by the action of capillary instabilitiesgives place to the formation of an aerosol of structured droplets which,under the action of a source of ultraviolet light, allows encapsulationof the inner liquid.

General Device Illustrated in the FIGURE. A device 100 used to producestable charged coaxial jets of non-miscible liquids with diameters inthe micro/nanometric range and the subsequent aerosol of structuredmicro/nano particles or capsules for addition to food is shown anddescribed herein (see the FIGURE). Of course, other embodiments of thisdevice can be used so long as they produce the desired aerosol ofstructured micro/nano particles or capsules for addition to food.Although various embodiments are part of the invention, they are merelyprovided as exemplary devices which can be used to convey the essence ofthe invention, which is the formation of stable coaxial micro jets ofmicro and nanometric diameters via EHD and/or uniform dispersion ofcharged structured micro/nano particles.

The basic device for using in the invention according to the FIGUREcomprises: (1) a means for supplying a first liquid 12 through ametallic tube 16, preferably with an OD of about 400 mm and ID of about200 mm; (2) a means for supplying a second liquid 10, non-miscible withthe first liquid 12, through a metallic tube 14, with an OD that issmaller than the ID of tube 16; (3) a counter electrode (ground) 24, orextractor, like a metallic plate, placed a short distance (e.g.,preferably about 1 mm) in front of the needle tips 18, having a hole 26therein; the center of the hole 26 is approximately located along, andaligned, with, the long axis of the needle tips; and (4) a high voltagepower supply, with one of the poles connected to needle 16 and the otherone connected to the counter electrode 24. Both needles or tubes 14 and16 may or may not be at the same electrical potential. In theconfiguration shown in the FIGURE, needle 14 is placed concentricallyinside of needle 16. The exit of the needle or tubes 14 and 16 may ormay not be located at the same axial position. All the components areimmersed in a dielectric atmosphere that may be a gas, liquid, orvacuum. A Tayor cone 20 forms at needle tips 18 and a micro structuredjet 21 forms from the portion of the Taylor cone 20 removed from theneedle tips 18. Part of the aerosol 22 formed, or even the microstructured jet 21, may be withdrawn through the hole 26 for furtherprocessing or characterization of the products. Of course, as thoseskilled in the art will realize, specific dimensions given here, as wellas through out the specification, can be varied so long as the desiredcapsules and particles for incorporation into food products can beobtained as described herein.

More specifically, the FIGURE provides a schematic representation of anapparatus 100 suitable for the formation of capsules and particles forincorporation into food products by generation of compound jets via EHD.A structured Taylor cone 20 forms at the ends 18 of the electrifiedneedles 14 and 16 when inner liquid 10 and outer liquid 12,respectively, are injected at appropriate flow rates through theirrespective needle tips 18. At least one needle (in this case needle 16)is connected at a potential difference 28 with respect to a referenceelectrode 24 which has a hole 26 there through. In one preferredembodiment, the potential difference 28 between the needles 14 and 16and the reference electrode 24 is a few kV. Two concentric jets 21, oneof them surrounding the other, issue from the tip (i.e., cone vertex) ofTaylor cone 20. The concentric jets 21 break up eventually by varicoseinstabilities giving rise to an aerosol of compound drops 22 with theinner liquid 10 (dark grey) surrounded by the outer one 12 (lightergray). Chamber 30 contains a dielectric atmosphere (i.e., gas, liquid,or vacuum) in which the compound drops 22 are formed. Compound drops 22can be removed from chamber 30 via hole 26.

If the electrical conductivity of one of the two liquids is high enough,a conical meniscus (Taylor cone) is formed at the exit of the needlewhen a sufficiently high voltage difference is applied between theneedle 16 and counter electrode 24. We shall call driving liquid the oneupon which the EHD forces act to form the Taylor cone. It is necessarythat EHD forces act on one liquid at least, although they may act onboth. We shall describe the configuration in which the “driving” liquidflows through the gap left between needles 14 and 16. A very thin(micro/nano) jet 21 issues from the Taylor cone 20 (i.e., the conevertex), the so-called cone-jet mode. The conical shape of the meniscusis due to the balance between surface tension and electric forces actingon the meniscus surface. The motion of the liquid is ignited by theelectric shear stresses acting on the cone's surface, which pulls theliquid towards the cone's tip. Other forces like dynamical pressurebecomes important at and beyond certain point of the conical interfaceof the electrified meniscus, and the interface changes from conical to ajet-like shape. The liquid mass ejected through the jet by EHD forces,should continuously be make up by an appropriate continuous supply ofliquid 12 through needle 16 to achieve a steady state; let this flowrate be Q_(A). The stability of this precursor stage depends through thecurrent/carried by the jet and the aerosol that is collected at 24.Depending on both the properties of fluid 12 and on Q_(A), the movementof liquid 12 inside the Taylor cone may be fully dominated by viscosity.In that case, the fluid velocity, anywhere inside the Taylor cone, isdominantly pointing towards the cone apex. Otherwise, the flow mayexhibit strong re-circulatory meridian motion and even swirl. Thesemotions should be avoided in order to produce coaxial jets via EHD. Ifthe flow of liquid 12 is dominated by viscosity, and a flow rate Q_(B)of liquid 10 is continuously supplied to needle 14, the meniscus ofliquid 10, formed inside the Taylor cone 20 developed by liquid 12, ispulled by the motion of liquid 12 towards the cone's apex. Under certainoperation conditions, which depend on the properties and the flow ratesof both liquids, the meniscus of liquid 10 develops a conical tip fromwhich a steady micro/nano jet of liquid is pulled by the motion ofliquid 12. In this situation, there might be regimes in which both jetsflow concentrically, that of liquid 10 being inside that of liquid 12.Again, to reach a steady state, liquid 12 should continuously besupplied to needle 14 at a certain flow rate Q_(B). The otherconfiguration is performed when the “driving” liquid 12 flows throughneedle 16 and the second liquid 10 flows trough the annular gap between14 and 16. In this case, the motion of the “driving” liquid does notneed to be dominated by viscosity.

Liquid 10 (i.e., the inner liquid in the desired capsules or particles)is in general a liquid formulation of a food, which is high innutritional value but has an unpleasant taste and therefore it would beof interest to coat it with a polymer or any other material with notaste.

The focusing effect of the electrical forces gives rise to jets withdiameters which can be thousand of times smaller in diameter than thediameters of the needles. This effect provides advantages such as (1)clogging of the exit needle is practically eliminated, and (2) thediameters of the coaxial jets and consequently the resulting particlesare much smaller than the diameters of the needles. This is desirablesince it is very difficult to engineer holes or tubes for liquidextrusion with very small diameters.

A variety of configurations of components and types of fluids willbecome apparent to those skilled in the art upon reading thisdisclosure. These configurations and fluids are encompassed by thepresent invention provided they can produce a stable electrifiedcone-jet mode of a first liquid. The liquid coming from a feeding needleforms a Taylor cone 20 at the exit port if the needle is connected to anelectrical potential whose value lies within of an appropriate rangewith respect to a reference electrode. A very thin electrified jet 21 isemitted from the cone vertex. A second fluid, non-miscible with thefirst one, can be injected at appropriate flow rates through a secondneedle, which is concentrically configured with respect the first one.This second needle can be connected to the same, or alternatively to adifferent, potential. A jet is issued from the tip of the more or lessconical meniscus of the second fluid, which is anchored at the exit ofthe second needle. This jet is accelerated by the first one through theaction of the viscous forces and flows coaxially it. The eventual breakup of the coaxial jets due to varicose instabilities results in anaerosol 22 of spherical droplets with an inner liquid coated by an outerone. The stability of the droplets can be maintained by a number ofprocedures. For example, they can be aspirated into a curing tube andirradiated by energy to harden or polymerize the outer coating. As anexample, lactose could be coated with a polymer coating, which would notdissolve in a dairy product (e g , milk or ice cream) but would dissolvein the gastrointestinal tract. It would make possible that lactaseintolerant individuals eat dairy products since lactose would combinewith the lactase enzyme after being consumed and its negative effect forthose individuals becomes neutralized.

The embodiment of the FIGURE is clearly designed to produce capsules ofone substance coated by another substance. Therefore, the outer feedingneedle is positioned concentrically with the inner one in the device inthe FIGURE. Furthermore, two or more additional feeding needles witheach one concentrically positioned around the preceding one may surroundthe inner needle. If several liquids are injected through the needles atappropriate flow rates and values of the needle voltage, the break up ofthe resulting coaxial multi-jets gives rise to an aerosol of dropletscomposed of several approximately concentric layers. The diameters ofthe spheres (inner and outer) can be precisely adjusted by varying theouter-inner flow rate ratio.

It should be emphasized that the diameters of the coaxial jets dependon: (1) the flow rates, (2) the properties of the two liquids, mainly onthe conductivity of the driving liquid, and (3) the applied voltages,but not from the diameters of the feeding needles. The former can bethousand of times smaller than the latter ones.

In the case of capsules of two materials, the material that willconstitute the nucleus of the capsule is steadily injected through theinner needle while the coating is injected between the inner and theouter tubes. One of the liquids (or both) acts as driver forming aTaylor cone under the action of the EHD forces from whose vertex anextremely thin jet is emitted. The other liquid is forced by viscousforces as a consequence of the motion of the driving liquid (or by acombination of both viscous and EHD forces if the electricalconductivity of the second liquid is also sufficiently high).

Formulation and composition of particles prepared using the presentinvention in food products. In the present specification and appendedclaims, the singular forms a, and, and the include plural referentsunless the context clearly dictates otherwise. Thus, for example,reference to a capsule includes a plurality of capsules and reference toa liquid includes reference to a mixture of liquids, and equivalentsthereof known to those skilled in the art, and so forth. Unless definedotherwise, all technical and scientific terms used herein have the samemeaning as commonly understood by one of ordinary skill in the art towhich this invention belongs.

The terms capsules, atomized particles, and atomized particles offormulation are used interchangeably herein and shall mean particles ofliquid formulations (preferably liquid food) that have been atomizedusing the device and method of the invention.

The term formulation as used herein refers to any matter to be atomized.A formulation may contain a single component to be added to the food, ormay contain multiple components. The term is also intended to encompassexcipients, carriers, and the like, including compounds to whichcomponents are conjugated, as described in the following sections.

The term food as used herein means (1) articles used for food (consumedby mouth for nutrition) or drink for man or other animals, (2) articlesused for components of any other such food article. Food includesarticles used by people in the ordinary way most people use food (i.e.,for taste, aroma, and/or nutritive value). The term food as used hereinis also intended to cover food additives (e.g., condiments) andspecialized foods such as infant formula.

The term food additive as used herein means any substance the intendeduse of which results or may reasonably be expected to result, directlyor indirectly, in its becoming a component or otherwise affecting thecharacteristics of any food, including any substance intended for use inproducing, manufacturing, packing, processing, preparing, treating,packaging, transporting, or holding food. The term as used herein doesnot include a pesticide chemical or a drug regulated by the Food andDrug Administration (as either a prescription or over the counter (OTC)drug) that has been added to the food. Examples of food additivesinclude components which by themselves are not additives such asvitamins, minerals, color additives, herbal additives (e.g., Echinacea,St. John's Wort, and the like), antimicrobials, preservatives, and thelike which when added to food are additives.

The term color additive as used herein includes a dye, pigment, or othersubstance that when added or applied to a food is capable of impartingcolor thereto.

The term infant formula as used herein refers to a food which purportsto be or is represented for special dietary use solely as a food forinfants by reason of its simulation of human milk or its suitability asa complete or partial substitute for human milk.

The term improved food as used herein refers to a food product that isimproved over a conventional food product by the addition of more of acomponent already present in the conventional counterpart. As used, theterm encompasses functional foods, but also includes food such as breadswith added carbohydrates, cereals with added vitamins and/or minerals,and foods in which undesirable components are reduced by the addition ofother more desirable components (e.g., replacement of fat with a fatsubstitute).

The term functional food as used herein refers to designed food withfunctional additives that effectively combine ingredients not usuallyfound together in a single food source. Functional foods have theappearance and structure of conventional foods but contain significantlevels of biologically active components that impart health benefits ordesirable physiological effects beyond basic nutrition. An example offunctional food is a food that is not normally high in fiber or proteinto which either fiber or protein is added. For example, the addition ofinsoluble fiber whose source is wheat bran to some foods may reduce therisk of breast or colon cancer.

The term nutriceutical as used herein refers to products produced fromfoods and/or natural sources (e.g., herbal extracts) that are sold inmedical forms such as pills, powders and potions.

The terms vitamins, minerals, vitamin and minerals, and the like as usedherein generally refer to nutritive food additives that may be found inor added to a food product. As used herein, vitamins supplements andmineral supplements are considered dietary supplements, and as they areseparate products they do not fall under the definition of food per se,but rather are considered to be nutriceuticals for purposes of thepresent application.

The term drug as used herein means (1) articles recognized in theofficial United States Pharmacopoeia, official Homeopathic Pharmacopoeiaof the United States, official National Formulary, or the Physician'sDesk Reference (PDR), any supplement to any of them; and (2) articlesintended for use in the diagnosis, cure, mitigation, treatment, orprevention of disease in man or other animals; and (3) articles (otherthan food) intended to affect the structure or any function of the bodyof man or other animals; and (4) articles intended for use as acomponent of any articles specified in (1), (2), or (3).

The methods described herein allow for the addition to food of a numberof different components but avoiding the contact between food andadditives. The functional components may be used alone or in combinationin the particles, which can be designed and sized for increasedbio-efficiency of the particles. Moreover, functional components may befound in the interior of the coated particle, as a layer in multilayeredparticles, or in the coating of particles produced in this invention.

Formulation components may also be inert materials that serve to coat afunctional particle, or provided a filler as a template to be coatedwith composition containing a functional particle.

For example, herbal extracts and/or the functional components of suchmay be added to foods, including beverages, chewing gums, and sportsbars using the present invention. Functional components likephyto-chemicals and/or other functional components that providephysiological benefits can be incorporated to food to bring thesebenefits to consumers. Some examples are sitostanol ester or otherbioactive ingredients such as omega-3-fatty acid and bifidogenic dietaryfibers which can help to lower cholesterol and to fight cardiovasculardisease. Carotenoids, collagen hydrolysate, flavonoids among othersfunctional components are additional examples.

Exemplary uses of the present invention. The present invention providesa method of coating one formulation with another formulation to formcapsules with diameters in the micro and nanometric range to be added tofood. The method is especially adapted for the introduction of a numberof components to food products, including multilayered functionalcomponents as described below. The method of the invention can be usedto coat functional components with a substance having a desirablequality for food flavor or texture (e.g., spices, seasonings, naturalflavorings, and the like). Thus, the present invention allows theincorporation of an effective amount of an enhancing or functionaladditive to a food product without adversely effecting the organolepticproperties of the food product. An “effective amount” is an amount ofadditive which provides the desired effect or benefit upon consumption.

The method of the invention can be used to produce food products havinggreater fiber content, while still maintaining the texture and taste oftheir conventional counterparts, by coating fiber particles with adesirable substance that enhances the flavor, texture, etc, of the food.For example, bran particles can be coated with another substance (e.g.,fat, oil or sugar), and to mimic the normal size of particles size infood (e.g., fat-coated bran particles can be produced to mimic thenormal size of fat globules in foods). This will preserve the flavorand/or feel of the food, and it may be helpful in creating foods thatare lower in fat, to decrease cardiovascular disease, or lower in sugar,for diabetics, without sacrificing the taste or texture of the foodproduct.

The device can be also used to coat proteins and/or specific amino acidsin food to make them higher in proteins and/or desired amino acids, butwith better taste and/or texture due to the substance that is coatingthe protein. Coating of other filler molecules, such as methylcellulose,casein, and the like, is also intended to be encompassed in the presentinvention. The use of such filler compositions, which preferably do notadd to the caloric nature of a food will be apparent to one skilled inthe art upon reading the present disclosure.

Foods with components having food additives coatings. As long as theeffectiveness of a food additive is due to its surface area, the use ofthe method of the invention may substantially reduce the amount ofadditives. For example, coating a filler particle without altering thecolor of a food or drink may reduce the amount of color additives thatare added to food products.

Food additives that may be used to coat a particle include, but are notlimited to, acidifiers, adjuvant of flavor, flavor enhancers among manyothers.

Foods with incompatible components. Foods having functional componentsthat are incompatible with the other ingredients of the food product mayalso be coated using the method of the present invention. For example,the addition of coated particles of lactase, which would be released inthe gastrointestinal tract, to a dairy product such as milk, cheese, orice cream would permit people affected with lactose intolerance todigest these products. The addition of coated amylase particles can alsofacilitate the digestion of certain high-fiber foods.

Other components that when added to a food may cause the food to changein nature of texture can also be added to a food by coating the particlefor release during digestion. The addition of gelatin to a beverage,which can be healthy for bones and joints, changes the nature of thebeverage at least gelatin is coated with the method of the presentinvention and after added to the beverage.

Foods fortified with components that alter taste. Minerals such ironcompounds can alter the taste of a food product but a coating that haseither a neutral flavor or a flavor that enhances the food product canmask this effect. Omega-3 fatty acids and garlic extract, which havebeen touted to lower cholesterol and triglyceride levels in the blood,can be coated to eliminate their negative influence on the flavor of thefood and to allow them to be added to a wide variety of foods.

The present invention is not limited to the particular components andsteps described above, as these may, of course, vary. It is also to beunderstood that the terminology used herein is for the purpose ofdescribing particular embodiments only and is not intended to belimiting, since the scope of the present invention will be limited onlyby th appended claims. All publications, including patents, referred toin the present specification are hereby incorporated by reference.

What is claimed is:
 1. A method for producing encapsulated particles tobe added to food products, said method comprising: forcing a firstliquid through a first exit opening in an electrified first feedingneedle to form a Taylor cone at the first exit whereby an extremely thinjet of the first liquid is emitted into a chamber having gas or vacuum;forcing a second liquid, non-miscible with the first liquid, through asecond exit in a second feeding needle, wherein the second feedingneedle is concentrically located with respect to the first feedingneedle, in a manner which causes the second liquid to form a conicalmeniscus which is anchored at the second exit of the second feedingneedle and surrounds the Taylor cone of the first liquid; wherein a jetof the second liquid, which is coaxial with, and surrounds, theextremely thin jet of the first liquid, is issued from the conicalmeniscus into the chamber; wherein the second feeding needle is at thesame or different electrical potential than the first feeding needle;wherein the chamber contains a dielectric atmosphere; wherein stablefluid interfaces are maintained between the second liquid and the gas orvacuum in the chamber and wherein the second and first liquids forcedfrom the first and second feeding needles form the encapsulatedparticles; and wherein the encapsulated particles comprise an inner coreof the first liquid and an outer layer of the second liquid and whereinthe encapsulated particles have an average diameter of about 100 micronsto about 15 nanometers.
 2. The method of claim 1, wherein the secondliquid forms a Taylor cone and first liquid is driven by the secondliquid.
 3. The method of claim 1, wherein the first liquid is a food orfood additive and the second liquid is a polymer material whichencapsulates the food or food additive.
 4. The method of claim 2,wherein the first liquid is food or food additive and the second liquidis a polymer material which encapsulates the food or food additive. 5.The method of claim 1, wherein the first liquid is a food or foodadditive with high nutritional value but offensive taste and the secondliquid is a polymer which encapsulates the food or food additive.
 6. Themethod of claim 2, wherein the first liquid is food or food additivewith high nutritional value but offensive taste and the second liquid isa polymer which encapsulates the food or food additive.